Update CI actions and generate Javadoc on JDK 21 (#1439)

This keeps us up to date and also moves us off of some deprecated
Gradle-related actions.

We also generate Javadoc on a more recent JDK version to get latest
Javadoc improvements.

.github/workflows/continuous-integration.yml

@@ -32,31 +32,21 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Check out WALA sources
-        uses: actions/checkout@v3
-      - name: Cache Goomph
-        uses: actions/cache@v3
-        with:
-          path: ~/.goomph
-          key: ${{ runner.os }}-goomph-${{ hashFiles('build.gradle') }}
-          restore-keys: ${{ runner.os }}-goomph-
+        uses: actions/checkout@v4
       - name: 'Set up JDK ${{ matrix.java }}'
-        uses: actions/setup-java@v3
+        uses: actions/setup-java@v4
         with:
           java-version: ${{ matrix.java }}
           distribution: 'temurin'
-      - name: Validate Gradle wrapper
-        uses: gradle/wrapper-validation-action@v1
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
       - name: Build and test using Gradle with ECJ
-        uses: gradle/gradle-build-action@v2
-        with:
-          gradle-executable: xvfb-gradle.sh
-          arguments: aggregatedJavadocs build publishAllPublicationsToFakeRemoteRepository shellcheck --no-configuration-cache -Pcom.ibm.wala.jdk-version=${{ matrix.java }}
+        # use xvfb-gradle.sh to avoid headless test failures on Linux
+        run: ./xvfb-gradle.sh aggregatedJavadocs build publishAllPublicationsToFakeRemoteRepository shellcheck --no-configuration-cache "-Pcom.ibm.wala.jdk-version=${{ matrix.java }}"
         # testing ECJ compilation on any one OS is sufficient; we choose Linux arbitrarily
         if: runner.os == 'Linux'
       - name: Build and test using Gradle but without ECJ
-        uses: gradle/gradle-build-action@v2
-        with:
-          arguments: aggregatedJavadocs javadoc build -PskipJavaUsingEcjTasks --no-configuration-cache -Pcom.ibm.wala.jdk-version=${{ matrix.java }}
+        run: ./gradlew aggregatedJavadocs javadoc build -PskipJavaUsingEcjTasks --no-configuration-cache "-Pcom.ibm.wala.jdk-version=${{ matrix.java }}"
         if: runner.os != 'Linux'
       - name: Check for Git cleanliness after build and test
         run: ./check-git-cleanliness.sh
@@ -84,18 +74,20 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Check out repository'
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Cache Goomph
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/.goomph
           key: ${{ runner.os }}-goomph-${{ hashFiles('build.gradle') }}
           restore-keys: ${{ runner.os }}-goomph-
-      - name: 'Set up JDK 11'
-        uses: actions/setup-java@v3
+      - name: 'Set up JDK 21'
+        uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 21
           distribution: 'temurin'
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
       - name: 'Generate latest docs'
         env:
           GITHUB_TOKEN: ${{ secrets.WALA_BOT_GH_TOKEN }}